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Diffstat (limited to 'src/detect-id.c')
| -rw-r--r-- | src/detect-id.c | 407 |
1 files changed, 407 insertions, 0 deletions
diff --git a/src/detect-id.c b/src/detect-id.c new file mode 100644 index 0000000..5239288 --- /dev/null +++ b/src/detect-id.c @@ -0,0 +1,407 @@ +/* Copyright (C) 2007-2021 Open Information Security Foundation + * + * You can copy, redistribute or modify this Program under the terms of + * the GNU General Public License version 2 as published by the Free + * Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +/** + * \file + * + * \author Pablo Rincon Crespo <pablo.rincon.crespo@gmail.com> + * + * Implements the id keyword + */ + +#include "suricata-common.h" +#include "decode.h" +#include "detect.h" + +#include "detect-parse.h" +#include "detect-engine.h" +#include "detect-engine-mpm.h" +#include "detect-engine-prefilter-common.h" + +#include "detect-id.h" +#include "flow.h" +#include "flow-var.h" + +#include "util-debug.h" +#include "util-byte.h" +#include "util-unittest.h" +#include "util-unittest-helper.h" + +/** + * \brief Regex for parsing "id" option, matching number or "number" + */ +#define PARSE_REGEX "^\\s*([0-9]{1,5}|\"[0-9]{1,5}\")\\s*$" + +static DetectParseRegex parse_regex; + +static int DetectIdMatch (DetectEngineThreadCtx *, Packet *, + const Signature *, const SigMatchCtx *); +static int DetectIdSetup (DetectEngineCtx *, Signature *, const char *); +#ifdef UNITTESTS +static void DetectIdRegisterTests(void); +#endif +void DetectIdFree(DetectEngineCtx *, void *); + +static int PrefilterSetupId(DetectEngineCtx *de_ctx, SigGroupHead *sgh); +static bool PrefilterIdIsPrefilterable(const Signature *s); + +/** + * \brief Registration function for keyword: id + */ +void DetectIdRegister (void) +{ + sigmatch_table[DETECT_ID].name = "id"; + sigmatch_table[DETECT_ID].desc = "match on a specific IP ID value"; + sigmatch_table[DETECT_ID].url = "/rules/header-keywords.html#id"; + sigmatch_table[DETECT_ID].Match = DetectIdMatch; + sigmatch_table[DETECT_ID].Setup = DetectIdSetup; + sigmatch_table[DETECT_ID].Free = DetectIdFree; +#ifdef UNITTESTS + sigmatch_table[DETECT_ID].RegisterTests = DetectIdRegisterTests; +#endif + sigmatch_table[DETECT_ID].SupportsPrefilter = PrefilterIdIsPrefilterable; + sigmatch_table[DETECT_ID].SetupPrefilter = PrefilterSetupId; + + DetectSetupParseRegexes(PARSE_REGEX, &parse_regex); +} + +/** + * \brief This function is used to match the specified id on a packet + * + * \param t pointer to thread vars + * \param det_ctx pointer to the pattern matcher thread + * \param p pointer to the current packet + * \param m pointer to the sigmatch that we will cast into DetectIdData + * + * \retval 0 no match + * \retval 1 match + */ +static int DetectIdMatch (DetectEngineThreadCtx *det_ctx, Packet *p, + const Signature *s, const SigMatchCtx *ctx) +{ + const DetectIdData *id_d = (const DetectIdData *)ctx; + + /** + * To match a ipv4 packet with a "id" rule + */ + if (!PKT_IS_IPV4(p) || PKT_IS_PSEUDOPKT(p)) { + return 0; + } + + if (id_d->id == IPV4_GET_IPID(p)) { + SCLogDebug("IPV4 Proto and matched with ip_id: %u.\n", + id_d->id); + return 1; + } + + return 0; +} + +/** + * \brief This function is used to parse IPV4 ip_id passed via keyword: "id" + * + * \param idstr Pointer to the user provided id option + * + * \retval id_d pointer to DetectIdData on success + * \retval NULL on failure + */ +static DetectIdData *DetectIdParse (const char *idstr) +{ + uint16_t temp; + DetectIdData *id_d = NULL; + int res = 0; + size_t pcre2len; + pcre2_match_data *match = NULL; + + int ret = DetectParsePcreExec(&parse_regex, &match, idstr, 0, 0); + + if (ret < 1 || ret > 3) { + SCLogError("invalid id option '%s'. The id option " + "value must be in the range %u - %u", + idstr, DETECT_IPID_MIN, DETECT_IPID_MAX); + goto error; + } + + char copy_str[128] = ""; + char *tmp_str; + pcre2len = sizeof(copy_str); + res = pcre2_substring_copy_bynumber(match, 1, (PCRE2_UCHAR8 *)copy_str, &pcre2len); + if (res < 0) { + SCLogError("pcre2_substring_copy_bynumber failed"); + goto error; + } + tmp_str = copy_str; + + /* Let's see if we need to scape "'s */ + if (tmp_str[0] == '"') + { + tmp_str[strlen(tmp_str) - 1] = '\0'; + tmp_str += 1; + } + + /* ok, fill the id data */ + if (StringParseUint16(&temp, 10, 0, (const char *)tmp_str) < 0) { + SCLogError("invalid id option '%s'", tmp_str); + goto error; + } + + /* We have a correct id option */ + id_d = SCMalloc(sizeof(DetectIdData)); + if (unlikely(id_d == NULL)) + goto error; + + id_d->id = temp; + + SCLogDebug("detect-id: will look for ip_id: %u\n", id_d->id); + pcre2_match_data_free(match); + return id_d; + +error: + if (match) { + pcre2_match_data_free(match); + } + return NULL; +} + +/** + * \brief this function is used to add the parsed "id" option + * \brief into the current signature + * + * \param de_ctx pointer to the Detection Engine Context + * \param s pointer to the Current Signature + * \param idstr pointer to the user provided "id" option + * + * \retval 0 on Success + * \retval -1 on Failure + */ +int DetectIdSetup (DetectEngineCtx *de_ctx, Signature *s, const char *idstr) +{ + DetectIdData *id_d = NULL; + SigMatch *sm = NULL; + + id_d = DetectIdParse(idstr); + if (id_d == NULL) + return -1; + + /* Okay so far so good, lets get this into a SigMatch + * and put it in the Signature. */ + sm = SigMatchAlloc(); + if (sm == NULL) { + DetectIdFree(de_ctx, id_d); + return -1; + } + + sm->type = DETECT_ID; + sm->ctx = (SigMatchCtx *)id_d; + + SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH); + s->flags |= SIG_FLAG_REQUIRE_PACKET; + return 0; +} + +/** + * \brief this function will free memory associated with DetectIdData + * + * \param id_d pointer to DetectIdData + */ +void DetectIdFree(DetectEngineCtx *de_ctx, void *ptr) +{ + DetectIdData *id_d = (DetectIdData *)ptr; + SCFree(id_d); +} + +/* prefilter code */ + +static void +PrefilterPacketIdMatch(DetectEngineThreadCtx *det_ctx, Packet *p, const void *pectx) +{ + const PrefilterPacketHeaderCtx *ctx = pectx; + + if (!PKT_IS_IPV4(p) || PKT_IS_PSEUDOPKT(p)) { + return; + } + + if (!PrefilterPacketHeaderExtraMatch(ctx, p)) + return; + + if (IPV4_GET_IPID(p) == ctx->v1.u16[0]) + { + SCLogDebug("packet matches IP id %u", ctx->v1.u16[0]); + PrefilterAddSids(&det_ctx->pmq, ctx->sigs_array, ctx->sigs_cnt); + } +} + +static void +PrefilterPacketIdSet(PrefilterPacketHeaderValue *v, void *smctx) +{ + const DetectIdData *a = smctx; + v->u16[0] = a->id; +} + +static bool +PrefilterPacketIdCompare(PrefilterPacketHeaderValue v, void *smctx) +{ + const DetectIdData *a = smctx; + if (v.u16[0] == a->id) + return true; + return false; +} + +static int PrefilterSetupId(DetectEngineCtx *de_ctx, SigGroupHead *sgh) +{ + return PrefilterSetupPacketHeader(de_ctx, sgh, DETECT_ID, + PrefilterPacketIdSet, + PrefilterPacketIdCompare, + PrefilterPacketIdMatch); +} + +static bool PrefilterIdIsPrefilterable(const Signature *s) +{ + const SigMatch *sm; + for (sm = s->init_data->smlists[DETECT_SM_LIST_MATCH] ; sm != NULL; sm = sm->next) { + switch (sm->type) { + case DETECT_ID: + return true; + } + } + return false; +} + +#ifdef UNITTESTS /* UNITTESTS */ + +/** + * \test DetectIdTestParse01 is a test to make sure that we parse the "id" + * option correctly when given valid id option + */ +static int DetectIdTestParse01 (void) +{ + DetectIdData *id_d = DetectIdParse(" 35402 "); + + FAIL_IF_NULL(id_d); + FAIL_IF_NOT(id_d->id == 35402); + + DetectIdFree(NULL, id_d); + + PASS; +} + +/** + * \test DetectIdTestParse02 is a test to make sure that we parse the "id" + * option correctly when given an invalid id option + * it should return id_d = NULL + */ +static int DetectIdTestParse02 (void) +{ + DetectIdData *id_d = DetectIdParse("65537"); + + FAIL_IF_NOT_NULL(id_d); + + PASS; +} + +/** + * \test DetectIdTestParse03 is a test to make sure that we parse the "id" + * option correctly when given an invalid id option + * it should return id_d = NULL + */ +static int DetectIdTestParse03 (void) +{ + DetectIdData *id_d = DetectIdParse("12what?"); + + FAIL_IF_NOT_NULL(id_d); + + PASS; +} + +/** + * \test DetectIdTestParse04 is a test to make sure that we parse the "id" + * option correctly when given valid id option but wrapped with "'s + */ +static int DetectIdTestParse04 (void) +{ + /* yep, look if we trim blank spaces correctly and ignore "'s */ + DetectIdData *id_d = DetectIdParse(" \"35402\" "); + + FAIL_IF_NULL(id_d); + FAIL_IF_NOT(id_d->id == 35402); + + DetectIdFree(NULL, id_d); + + PASS; +} + +/** + * \test DetectIdTestSig01 + * \brief Test to check "id" keyword with constructed packets + */ +static int DetectIdTestMatch01(void) +{ + uint8_t *buf = (uint8_t *)"Hi all!"; + uint16_t buflen = strlen((char *)buf); + Packet *p[3]; + p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP); + p[1] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_UDP); + p[2] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_ICMP); + + FAIL_IF_NULL(p[0]); + FAIL_IF_NULL(p[1]); + FAIL_IF_NULL(p[2]); + + /* TCP IP id = 1234 */ + p[0]->ip4h->ip_id = htons(1234); + + /* UDP IP id = 5678 */ + p[1]->ip4h->ip_id = htons(5678); + + /* UDP IP id = 91011 */ + p[2]->ip4h->ip_id = htons(5101); + + const char *sigs[3]; + sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; id:1234; sid:1;)"; + sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; id:5678; sid:2;)"; + sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; id:5101; sid:3;)"; + + uint32_t sid[3] = {1, 2, 3}; + + uint32_t results[3][3] = { + /* packet 0 match sid 1 but should not match sid 2 */ + {1, 0, 0}, + /* packet 1 should not match */ + {0, 1, 0}, + /* packet 2 should not match */ + {0, 0, 1} }; + + FAIL_IF_NOT(UTHGenericTest(p, 3, sigs, sid, (uint32_t *)results, 3)); + + UTHFreePackets(p, 3); + + PASS; +} + +/** + * \brief this function registers unit tests for DetectId + */ +void DetectIdRegisterTests(void) +{ + UtRegisterTest("DetectIdTestParse01", DetectIdTestParse01); + UtRegisterTest("DetectIdTestParse02", DetectIdTestParse02); + UtRegisterTest("DetectIdTestParse03", DetectIdTestParse03); + UtRegisterTest("DetectIdTestParse04", DetectIdTestParse04); + UtRegisterTest("DetectIdTestMatch01", DetectIdTestMatch01); + +} +#endif /* UNITTESTS */ |